There is a known method in the related art for tracking specific cells to observe time-series changes of the form (shape, brightness, etc.) and the dynamic characteristics of cells contained in biological tissue (for example, refer to PTL 1). The method for tracking cells disclosed in PTL 1 is designed to track cells by processing images of cells acquired at certain time intervals to extract the outlines of the cells, and performing matching of the cells in the images acquired at different times to obtain the moving distances and the rotation angles thereof.